A waterboarding scene from Marat/Sade, directed by Anthony Neilson at the RSC. Photograph: RSC

The Royal Shakespeare Company's 50th anniversary revival of Marat/Sade in Stratford-upon-Avon has prompted mass walkouts.

An average of 30 people a night are reported to have left Anthony Neilson's new production of Peter Weiss's play before the end, with one audience member describing it as "utter filth and depravity". As well as enactments of waterboarding and skin being burnt, Neilson's revival features a simulated sodomy with sex toys and the Marquis de Sade being tortured with a stun gun.

Kate Day, a 25-year-old who left during the interval, said: "It was utter filth and depravity. The rape scene came just before the interval and many people did not return for the second half. There are ways one can stimulate an audience with dignity and guile, but this performance lacked any such wit. I think they have got it badly wrong. I don't blame people for walking out. They took it too far this time."

Set in a mental asylum during the French revolution, Weiss's play shows inmates re-enacting the last days of political agitator Jean Paul Marat's life under the direction of the Marquis de Sade, a role currently played by Jasper Britton.

Peter Brook's original production starred Glenda Jackson and is now considered one of the 20th century's seminal productions. Though it courted controversy and walkouts during its run at the Aldwych theatre in 1964, the production proved a success on Broadway, running for 145 performances and winning the Tony award for best new play. Brook later directed a film adaptation.

The RSC's artistic director, Michael Boyd, defended the production, but admitted that it had the potential to cause offence. "It's a controversial play because the subjects it explores – insanity, individuality, sexuality, the abuse of power, freedom versus control – are just as sensitive today as they were in the 1960s.

"Theatre should bring people together and take the risk of sharing sensitivities in public," said Boyd.

In his three-star review, the Guardian's Michael Billington wrote: "My objection is to the overkill in the actual staging. Unable to leave well alone, Neilson bombards us with shock effects." Citing Antonin Artaud, the theatre theoretician whose Theatre of Cruelty underpins Marat/Sade, Billington dismissed the production as "Artaud for Artaud's sake."

A spokesperson for the RSC said: "Everyone who booked was sent a letter in advance about the nature of the play, and many people are expressing positive comments."